proper US specifications for moveable equipment structural design

Can you advise on what the most appropriate standards (for the loads and structural design of moveable equipment) to cite should be when writing specifications to procure a fabricated piece of equipment in the US such as a moveable stack-out or recliamer, or a traveling gantry used for loading and unloading material, or articulating / traveling boom? In the past, we have adopted or adapted FEM or ISO standards for equipment manufactured overseas. We have also used common US standards to identify loading and design such as IBC, ASCE-7, AISC, and AWS, but their loading and design is mostly geared toward commercial buildings. A review of ASME 30.16, 30.18, and 30.22 did not seem to address the design loading and stress aspects.